Shaped charge warheads

ABSTRACT

Shaped charged warheads are filled with an explosive mixture consisting entirely of materials selected so that the warheads contain only finer particle sizes ranging between 0.05 microns up to about 200 microns.

Unlted States Patent 1 1 3,763,784

Mallory Oct. 9, 1973 SHAPED CHARGE WARHEADS 2,999,743 9/1961 Breza et a1 149/111 3,145,656 8/1964 Cook et al... 102/24 HC [75] gzf Chm Lake 3,241,489 3/1966 Andrew et a1. 102/27 HER PUBLICATI [73] Asslgnee: The United States of America as OT 0N8 represented by the secretary at the Cook, M. A. The Science of Hlgh Explosives. N.Y. Navy Washington DC Reinhold 1958. [p. 44-49, 129, 130. T1. 270G76C.2]

[22] Filed: May 1968 Primary Examiner-Verlin R. Pendegrass [21] App], M 734,188 Attorney-George J. Rubens, Roy Miller and Gerald F. Baker [52] U.S. Cl. 102/56, 102/24 l-IC 511 1111. C1. F42b 13/10 [57] ABSTRACT [58] Field 6: Search 149/110, 111, 115; hap a g d arh ad ar fill d ith an xpl s e 102/24 HC, 27, 56 mixture consisting entirely of materials selected so that the warheads contain only finer particle sizes [56] References Cited ranging between 0.05 microns up to about 200 mi- UNITED STATES PATENTS Precoul 102/56 X crons.

1 Claim, 7 Drawing Figures minnow 91m 3.763.784

A sum NF 3 I N VEN TOR. HERBERT D. MAL O BY ROY MILLER ATTORNEY. GERALD F. BAKER AGENT.

PATENTEBnm 9:915

SHEET 30F 3 F IG FIG. 7.

1 SHAPED CHARGE WARHEADS Government Interest The invention described herein may be manufactured and used by or for the Government of'the United States of America for govemmentalpurposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION 7 Explosives for military purposes are commonly selected because of their relative sensitivity to initiation, brisance, and suitability for melt-loading.

Of the dozen or so standard noninitiating high explosives used for military purposes, only TNT melts at a temperature below 100 C. and'can be melt-loaded with the use of low pressure steam kettles. As meltloading offers great advantages over press-loading, there have been developed binary explosives that consist of mixtures of TNT with another explosive or with another explosive and minor portions of additives such as desensitizing and binding agents. This has made available explosives that are superior to TNT alone with respect to fragmentation and blast effect.

Since the second explosive is selectedfor its desirable qualities such as superior brisance, low cost, etc., it follows that the ratio of the second explosive to TNT should be as high as practical. However, as a practical matter there are distinct limitations with respect to the proportions of other explosives that can be mixedwith TNT and melt-loaded. In the preparation of such mixtures it has been found that if the majority of the particles of the second explosive range from about 200 p. to about 1000 t that a higher percentage of the second explosive can be added without adversely affecting pourability. Because it was believed that particle size was of little or no significance in warhead detonation, the finer materials have usually been rejectedor have been used, for example, in low proportion mixes.

A technique has been developed'which allows-observation of small scale pressure irregularities wthin and behind the detonation wave of condensed explosives. (H Dean Mallory, Evidence of Turbulence in the Reaction Zone of Detonating Liquid Explosives, J. Appl. Phys. Vol. 37, No. 13, 4798-4803 (Dec. 1966).) The technique, which involves an impedance mirror, is independent of self-luminosity and permits investigation of the presence of pressure irregularities-within and behind the detonation front. The results have shown that strong turbulence is present in the dentonation flow of some liquids. (H. Dean Mallory, Turbulent Effects in Detonation Flow Diluted Nitromethane", J. Appl. Phys, Vol.38, No. 13, 5302-5306 (Dec. 1967).) Contrary to popular belief, it was my opinion that the presence of large particles in warheads of conventionalv manufacture was a major cause of pressure irregularities within and behind the detonation wave of the explosive and that such irregularities to a large extent affected the efficiency and effectiveness of the warhead.

Development of shaped charge devices (Birkhoff et al., Explosives with Lined Cavities, J. Appl. Phys. Vol. 19, 563-582 (June 1948).) raised questions concerning the mechanics of jet formation by a detonation front but, in line with popular belief, mixtures containing larger particles were used in thses devices because manufacturing techniques dictated that the mixtures be easily pourable in the molten state.

SUMMARY OF THE INVENTION Tests of shaped charge devices with warheads comprising materials with particle sizes ranging less than 200 p. have indicated that a smoother detonation front striking a shaped charge liner minimizes liner distortion during jet formation, thus making these shaped charge warheads much more efficient without the necessity of increasing warhead size. This increased efficiency is considered to be especially important in bomblet type weapons where large numbers of bomblets are required to increase hit probability. Greater effectiveness is realized with the present invention because of the decreased liner distortion which yields a jet having much greater penetrating power for agiven volume of explosive material than was thought possible.

The invention thus contemplates the exclusion of particles greater than 200 p. in the manufacture of shaped charge warheads, in spite of manufacturing difficulties, because of the resulting significant increase in penetrating power relative to warhead size and weight.

Brief Description of the Several Views of the Drawing FIG. 1. is a perspective view partially in cross section of a weapon component comprising a linear shaped charge warhead;

FIG. 2 is a cross sectional-view of the component of FIG. 1 taken along line 2 2 of FIG. 1;

FIG. 3=is a perspective view; partially in cross section, of a weapon comprising a conical shaped charge device;

FIGS. 4 and 5 are sequential framingcamera photographs of impedence mirror patterns from a conventional explosive mix; and

FIGS. 6 and7 are sequential framing camera photographs of impedence mirror patterns from an explosive mix according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION Two typical shaped charge devices are shown on the drawing to illustrate the type of devices contemplated by the invention. However, the invention is not intended to be limited to military applications since it is obvious that the improved results will be appreciated commercially as, for example, in the perforation of oil wells and in rock excavation.

A linear shaped charge warhead 10 is shown in FIG. 1 comprising a cylindrical outer casing 12 within which is the explosive mixture 14 enclosed in a peripheral liner 16.

The warhead conventionally is manufactured by pouring the explosive mixture 14, while in a molten state, into liner 16. The explosive mixture solidifies and the resulting assembly is placed in the outer casing 12.

The line 16, as illustrated in FIG. 2, has vane angles (angles of concavity) approximately but the optimum vane angle may vary with different liner materials and explosives as well as with the purpose. For current military purposes, the optimum vane angle in linear shaped charge devices ranges from about 120 to about In FIG. 3 a small conical shaped charge device 20 is shown filled with an explosive 14' fitted with a cone shaped liner 16'. The explosives preferred in these devices include I-IMX in Octol and RDX in Composition B. These materials possess high strength and, when detonated, produce a high velocity detonation front very rapidly reaching maximum velocity.

The effectiveness of shaped-charge warheads depends upon the formation of a well-aligned jet having the proper distribution of velocities along its path. It is well known that small initial asymmetries in a liner will degrade jet performance. On the basis of tests performed in the realization of the present invenion it is evident that small assymmetries produced in the liner by impact of a rough detonation wave also degrade jet performance.

In FIGS. 4 and 5 respectively sequential views are shown of a detonation wave front impression on a metal target. These wave front photographs were made possible by the use of the impedence mirror technique mentioned earlier and represent an explosion of a runof-the-mill explosive mixture having particle sizes ranging up to about 1,000 ,u.

The irregularities apparent in the wave front are at tributed to the larger particles in the explosive mixture.

FIGS. 6 and 7 represent similar sequential views of a wave front from the detonation of an explosive mixture wherein the particle size was limited to from about 0.05 t to about 200 it. Detonation front aberrations are very noticeably diminished in these photographs as contrasted with FIGS. 4 and 5.

From the foregoing it will be appreciated that shaped charge warheads may be expected to perform much more effectively and efficiently when manufactured from explosive mixtures with particle sizes less than about 200 p.

What is claimed:

1. A shaped charge explosive device comprising a detonatable explosive mixture formed with at least one concavity lined with a jet forming liner wherein said mixture consists of an explosive matrix material of relatively low melting point; and

a second explosive material dispersed in said matrix material and wherein said second explosive material consists entirely of particles smaller than about 200 u. 

